Art of amalgamating silver ores



(No Model.)

A. J ANIN. ART 0F AMALGAMATING SILVER ORE.

Patented Ap'r. 19,1892.

.xiii

Nrrnn raras ArnNr OFFICE.

ART OF AMALGANIATING SILVER ORES.

SPECIFICATION forming part of Letters Patent No. 473,395, dated April 19, 1892.

Application iled September lI 1891. Serial No. 404,453. (No model.)

To all whom, it may concern:

Beit known that I, ALEXIS JANIN, a citizen of the United States, residing in the city and county of San Francisco, State of California, have invented certain new and useful Improvements in the Art of Amalgamating Silver Ores, of which the following statement is a specification, reference being had therein to the accompanying drawings, which form part of this specification.

Figure 1 is a Vertical section on the line x' a'. of Fig. 2. Fig'. 2 is a plan View of Fig. l.

Myinvention relates to an improved method of and apparatus for chloridizing silver ores by means of an acid solution offerric chloride prior to the amalgamation of the ore in iron pans. By an acid solution I mean one that will not deposit iron when heated or which contains or is used in connection with enough free acid to overcome the action of substances in the ore to be treated, which would otherwise decompose the solution of ferrie chloride. It is well known that ferrie chloride is a powerful chloridizing agent; but its use in connection with thepan amalgamation process has hitherto been precluded, owing to the fact that both the iron of the pan and the mercury or amalgam constantly remaining in the pan will reduce the ferric chloride to ferrous chloride, which latter salt has little, if any,l

effect in chloridizing silver minerals. l/Vhen the chloridizing of the ore by means of ferrie chloride. and its subsequent amalgamation are both carried out in wooden apparatus-such as revolving barrels-then the grinding action and violent motion of the iron pan are forfeited, and the practical operations require more time and are more expensive than by the method I have invented. This consists in heating the ore, together with an acid solution of ferrie chloride, in a preparatory apparatus constructed of material that will not destroy or which will only be slightly aiected bythe solution of ferric chloride, and then completing the amalgamation in iron pans in the usual Way. If there still remain an excess of ferrie chloride in the pulp after the chloridizing of the silver minerals in the preparatory apparatus has been effected, I add to the pulp a substance or substances which will neutralize the free acid present and reduce the ferrie chloride to ferrous chloride or precipitate its iron as an oxide prior to the introduction of mercury into the pulp, and which will also precipitate in harmless forms other metallic salts which may have been brought into the solution by the action of free acid or of ferrie chloride on baser minerals contained in the ore, which salts would otherwise have an injurious eect upon the mercury used in the amalgamation of the ore. This is notably the case when chloride of copper is present in the solution, and my method of precipitating metallic `salts from their solution prior to the introduction of mercury into the pulp can also be applied with advantage'when silver ore is chloridized by means of sulphate ofr copper and salt prior to its amalgamation in iron pans. f

My process is applicable to ores of which the gangue is mainly silicious. stances Which would decompose ferrie chloride-such as carbonate of lime-are also present in the ore, their action must be overcome by the addition of acid to the ore. The small cost at which the solution of ferric chloride can be produced permits of its use in large proportions, and my method of rendering any excess of free acid or of metallic salts harmless before discharging the pulp into the iron pan or before the introduction of mercury into the pulp reduces to a minimum theconsumption of that metaland of the iron of the an. p An acid solution of ferric chloride will chloridize most of the nobler silver minerals, and is especially adapted to the treatment of arsenical compounds and fahl-ores. ,It hasalso the advantage of producing tine"'-b'illi'oii', whereas when sulphate of copper andffs'alt are used in chloridizing silver ores the copT per will be partially amalgamated, whether the chloridizing action takes place in afseparateapparatus or not. Neitherjwill the use ofa separate chloridizing apparatus prevent the injurious action of chloride of copper upon the mercury added in the iron pan, unless the copper be first precipitated from its solution by the method I have invented. ,Y

The chloridizing of the silver minerals by When sub- IOO ` `j The chloridizing-tubAisplaced at a higher sides of the tub.

pacity as an amalgamating-pan and runningy two and one-halt hours on each charge can supplytwo amalgamating-pa'ns running five hours and charged `alternately at intervalsl 1 low. o The J valve arrangement tordischargoftwoV androne-half hours. l

"jfldy giving thechloridizing-tub double the capacity of anlamalgamatingpan tour` otl the latterfcain besuppliedby one of the former,` :two alternate pans in the row being charged atone time and Ahalt hoursflater.`

levelithan the amalgamatingpan J, and the Qthe other two two andone-Q twoare connected by means of`a system ofv troughs l1 or pipes provided with gates 1I or switches, which connection permits ofthe si-r multaneous charging of two pans. These.

'gates t' may be ot` `any ordinaryform. of adjustablelor "movable plates controlling the owof the material through the troughs into thepans. 1

Inithe accompanying drawings,iFigi 1re l is `afverticalsection, and l `,1g.2 a p1an,of the chloridizing-tub A, showing the method 'ott vconnecting the same with four amalgamat ing-pans J, which are themselves connected with two` settlers, the latter being unnecessaryito show. The valve arrangement is for opening and 'closing the discharge-orifice of thechloridizing-tubwithout using loose plugs. By means of this valve theffiow of pulp from` thetublto the pan can Abe regulated or interrupted at any moment, and-when the pre-'1 paratorytub holds a charge fortwo amalgamating-pans permits drawing off a charge Vfor? one pan onlyLif the other should be temporarly outfof order. The sides of the chlorid-l izing-tub are formed ofy wooden staves, rest-5` ing on a` cast-iron bottom a, provided with al `flange. Wooden wings a are attached to thel The stirring ap paratus may be of any suit-l able character. 'lo it lkgiveaspeedofthirty-t verevolutions per minute when the tub has, adiameter of six `feet; It is driven by a ver-l tcalsh'aftE passing through `a cone a2, and can `be raised or `lowered by means of set-i screws e The legs D of =the.stirring appa-1 ratus are of scantling of suitable dimensions' and have horizontal arms d. These arms,

well as the iron cone and the iron bottom of `the pan, should be suitably protected from the action of the chemicals by covering them 65 with any material, such as wood for the arms, a sheathing of lead or wood for the cone, and a layer of cement for the iron bottom. These portions of the apparatus are, however, but little acted upon by chemicals when the pulp is thick, and there being no grinding action `in the chloridizing-tub a removable iron die maybe used to protect the permanent bottom, or the cone and shaft may be dispensed with and thestirringapparatus run on a collarabove thetub and be driven by overhead gearing, all such 'modifications being well known and requiring no illustration. In the present instancelhave shown the shaft E as being driven by means ofgearingEfrom be- Ying the -`contents ofethe.:.chloridizing-tub, as shown in thedrawings, consists of` a box F,

4tting closelyagainst the side ofythe tub,be

yondvwhich the` iron.dischargenozzle `f projects, anda valve-stem G, entering the box at `right angles .to the` sideof the `tub ,and terminatin g in a head g of greater diameter than the disch arge-orifice. against which it presseswhen the valveis closed. The head of the valvestem is covered with.:leather or Vother flexible matcrial. The stem has its threaded bearing in a nut g2 outsidethe wooden box,.andby means of the hand-screw g` .the `discharge-orifice can be openedor closed, as desired. .This

.construction avoids contact of the .thread ot' the valve-stem with the pulp, and `also allows the stem to becleaned olf when required, as

it is easily accessible by `remo'vingthe cover of the box. By having. two discharge-holes in each tub the emptying ofthe tub can be .more Vrapidly effected. The walve arrangement can be constructed in its details in other formsthan l have described; `but.` its essence lies in the` application to a chloridizing apparatus `of the methodof regulating or interrupting the outflow of the pulp without `theuse ot" loose plugs, for the purposes described. l

N'Vhen the ore naturallycontains ferrie oxide,.easily soluble in` dilute acid, or. if. suchbe added to the ore, the solution lof ferrie chloride can be. formed by adding, hydrochloric acid or saltand snlphuricacid to the ore'. NVhen this method is not available, thesolution of Iferric chloridemay be economically formed by adding chloride of lime to a solution containing lhydrnchloric acid or sulphuric acid in excess of the amount necessary to liberate the chlorine of the chlorideof limelas gas, in the presence of iron vitriol `in solution with kcom mon salt, or of iron sulphides, either 1in contact wit-l1 the'ore or prepared separately. In this way threepounds of commercial chloride of lime will oxidize to ferrie chloride the iron contained in about eight pounds of iron vitriol in solution with common salt. By the same method iron sulphides contained in the IOS ITO

l-rrase e ore can be converted into ferric chloride. It is advisable to use both salt and acid in some excess.

The absolute amount of ferric chloride which may be required to chloridize the silver minerals in a given weight of ore will vary with the nature of the ore. Many sulphides of the baser metals--such as sulphides of copper, lead, antimony, and arsenicare slowly decomposed by a solution of ferrie chloride, which is itself at the same time reduced to ferrous chloride,which latter combination has no further action in chloridizing silver minerals. yIt is therefore necessary that ferrie chloride be present in such quantity that there will always remain enough in solution to effect the chloridizing of the silver minerals present in the same ore with baser sulphides. Sulphides of iron, however, are not acted upon by a solution of ferric chloride. Vhen the ore contains a large excess of sulphides of the baser metals other than the sulphides of iron, it is not well adapted to treatment by this method. In a given case the exact strength of the ferric chloride solution is to be determined by the yield of the ore when using solutions of different strength.

The ferrie chloride should always be present in such quantity as to effect the chloridizing of the silver minerals before the ferric chloride itself be decomposed by sulphides of the baser metals, if any such be present.

The practical operations in treating the ore are essentially as follows: The pulp is charged into the chloridizing-tub Awhile the stirring apparatus is in motion. Steam is then introduced directly into the pulp by suitable means, as by the pipe H. If the ore contains substances which would decompose ferrie chloride, their action is neutralized by the addition of free acid to the ore. The ore is now subjected to the action of a solutionof ferrie chloride, and the introduction of steam is continued until the temperature reaches 150 Fahrenheit or more. The steam is then shut off, and the mixing of the pulp by the stirring apparatus is continued until the silver minerals are chloridized, which will generally require from two to two and one-half hours from the time of charging. I then add to the pulp a substance or substances that will reduce the ferrie chloride present to ferrous chloride or precipitate the iron as hydroxide. If other metallic salts which would have an injurious effect on mercury are present in solution, they are precipitated by similar means. For this purpose there may be usediron boi-ings, which will reduce the ferrie chloride to ferrous chloride or carbonate of manganese or carbonate of lime or caustic lime or other similar substances, which will precipitate the metallic salts as carbonates or hydroxides. The reduction of ferrie chloride to ferrous chloride can also be accomplished by adding to the pulp granulated Zinc or sodium sulphite or by introducing, slowly, sulphurous-acid gas into the mixture of ore and solution until the reduction of the ferrie chloride is effected. The valve g, attached to the chloridiziiig-tub, is then opened, and the pulp is discharged through the conveyingtroughs I directly into one or more amalgamating-pans J.

If ferric chloride is only present in small amount in the chloridizing-tub when the same is to be discharged, the reduction of the iron to harmless forms byadded substances can be dispensed with, as it would be effected by the iron of the amalgamating-pan; but if present in large quantities the iron of which the pan is composed would be rapidly consumed, and the method I have described should be followed.

Having fully described my invent-ion,I do not claim in its entirety the method of first chloridizing silver ore by means of metallic chlorides in a preparatory apparatus and then anialgamating it in iron pans; but

1. The improvement inthe art of amalgamating silver ores, which consists in subjecting the ore in a preparatory or chloridizing apparatus to the action of an acid solution of ferric chloride, with assistance of heat, agitating the mixture of ore and solution until the silver minerals are chloridized, then discharging the pulp into an amalgamating-pan, adding mercury, and concluding the amalgamation in the usual way, substantially as described.

2. The improvement in the art of amalgamating silver ores, which consists in heating the ore in a preparatory or chloridizing apparatus, together with a solution of metallic chlorides, agitating the mixture of ore and solution until the silver minerals are chloridized, then adding a substance or substances that will neutralize free acid present and reduce ferric chloride to ferrous chloride or precipitate' the metallic salts in solution as carbonates or hydroxides, then adding mercury, and concluding the amalgamation in an amalgamating-pan in the usual way, substantially as described.

3. The improvement in the art of amalgamating silver ores, which consists in first heating the ore in a preparatory or chloridizing apparatus, together with an acid solution of ferrie chloride formed by mixing common salt and sulphuric or hydrochloric acid with chloride of lime in the presence of ferrous sulphate or of sulphides of iron, and then concluding the amalgamation in an amalgamating-pan in the usual way, substantially as described.

4. The combination of a chloridizing-tub having a discharge-opening, a stirring mechanism within said tub, a box inclosing the discharge-opening of the tub, a valve-stem passing through the outer wall of the box, hav- IOO ingu valve on its inner end, and u bearing eXtet rior ofthe outerwall'of the box and threaded to receive a .threaded portion of the stem substantially as herein described. i

5.'The eolnbinationof a ehloridizing-tub having strringfrneehansm and discharge-outletfamalgamating-pans at a level below the ohloridizing-tub, a box inolosing the outlet of the tub, and troughs interposed between the 1o tub and pans, :t valve-stem passing through the outer Wall oftheibox, havingv a valve on tsinner end and a hand-wheelat its outer end, and a bearing exterior of the box .for l said stem, substantially as. hereinideseribed.

- In witness whereof I have hereunto set my x5 hand. i l

i f ALEXIS J ANIN Witnesses:

S. H. NoURsE, J. A. BAYLEss. 

